The theoretical temperature dependences of the entropy and heat capacity near the phase transitions in considering the phenomenological model describing the sequence of phase transitions in the mineral lawsonite were calculated. Comparison of theoretical curves with the experimental results showed good qualitative agreement.
S.V. Pavlov, R.A. Romanov Department of general physics and condensed matter physics, Faculty of Physics, M.V.Lomonosov Moscow State University. Moscow 119991, Russia.